This application claims the benefit of International Application Number pct/se99/02103, which was published in English on Jun. 15, 2000.
The present invention relates in general to equipment for treating products continuously in a climate chamber by circulating a gas or gas mixture, air or steam around these. The invention relates in particular to what is known as a helical freezer and a flexible, self-stacking conveyor belt intended for use in this freezer, which belt is in the form of an endless loop, a part of which forms a number of helically running layers stacked one on another. A refrigerating medium is then circulated around the products present on the belt.
In addition to freezing, climate chambers with a belt of this type can also be used for other types of treatment of products, such as cooling, heating, boiling, sterilizing, drying, moistening etc. of products.
Climate chambers of this type have great capacity and afford good production economy because they allow continuous mass-treatment of products and require a relatively small amount of space.
The length of the endless loop of the conveyor belt and the speed of the latter are adapted so that the products have the requisite dwell time in the climate chamber for the treatment required. For maximum utilization of the space in a climate chamber of given dimensions, the belt must then be made so that it has the maximum possible useful loading area and so that the belt can be stacked in layers located one on another with the minimum possible construction height. The belt must also allow gas flows to be directed at the products in both the vertical and the horizontal direction at the same time as having a flexibility which allows it to be bent in the vertical direction both upwards and downwards and to form bends in at least one direction in the horizontal plane.
Climate chambers of this type with flexible conveyor belts are as described in, for example, EP 0 333 565, U.S. Pat. No. 5,190,143, U.S. Pat. No. 5,247,810 and U.S. Pat. No. 5,460,260.
The arrangement according to EP 0 333 565 comprises a belt with side walls formed by plates which are borne by the individual links in the belt. These side walls impede gas flows in the horizontal direction. Moreover, the belt is not self-stacking because it is supported by support rails along its inner edge. The freezer also contains a refrigerating machine, which increases the dimensions considerably as well as the air volume which has to be cooled to freezing temperature.
U.S. Pat. No. 5,347,810 and 5,247,810 also describe arrangements, in which the links of the belt are made with side plates which impede the gas flow. These plates also limit the width of the useful loading area of the belt.
In the arrangement according to U.S. Pat. No. 5,460,260, the side plates of the links used in the arrangements according to the patent specifications mentioned above have been replaced with stirrups which allow gas flow in the horizontal direction also. This known conveyor belt can be assembled to from an endless loop, a part of which forms a number of layers stacked one on another. To this end, the belt is constructed from mutually articulatable links which each comprise at least two transverse rods which, at each side edge of the belt, bear support members projecting upwardly from the plane of the belt, which are adapted so as to be capable of supporting a belt layer lying above, and which links are interconnected so that they can be displaced relative to one another along at least one side edge of the belt.
The stirrups serving as support members are welded firmly to plates which are arranged on the transverse rods of the belt inside outer connecting links which guide and interconnect the rods in parts. This results in inter alia the useful loading width of the belt being reduced considerably. Furthermore, the mounting of the stirrups by welding to carrier plates, which have to be slipped onto and fixed to the transverse rods, necessitates the number of production stages being increased, which prolongs the production time and increases production cost. The angled portions of the stirrups welded firmly to the plates also have disadvantages from the point of view of hygiene because pockets which collect dirt and are difficult to clean are formed between the angled portions and the associated plate.
One object of the present invention is to provide a flexible conveyor belt of the type described above, which comprises stirrup-shaped support members which allow helical self-stacking in a very reliable manner without encroaching appreciably on the useful loading width of the belt. Furthermore, the stirrups are to be capable of being mounted in a rational and cost-saving manner and so that it is easy to maintain higher hygiene standards during use of the belt.
To this end, the support members are connected to the ends of the transverse rods in the belt or constitute extensions of these rods, each support member comprising a stirrup-shaped support portion which projects upwardly from the plane of the belt and interconnects the rods in an associated link of the belt.
By virtue of the fact that the stirrups are connected to the ends of the transverse rods of the belt, the mounting of the stirrups does not encroach on the useful loading width of the belt. Furthermore, it is not necessary for any separate mounting plates to be arranged on the rods because the stirrups can simply be jointed to the ends of the transverse rods by using jointing sleeves which are stamped or welded firmly onto the rods. This renders production and maintenance less expensive and also allows improved hygiene during use of the belt.
The invention also relates to a climate chamber, in particular for what is known as a helical freezer, with a self-stacking conveyor belt of the type indicated above.
In this connection, one object is to provide as compact a helical freezer as possible, which requires a belt with a large effective loading area. According to the invention, the need for a refrigerating machine arranged in the freezer is eliminated by virtue of freezing being effected by means of cold gas from an external source, which also contributes to compact construction.
The invention also relates to a method for continuous treatment of products in such a climate chamber, according to which a gas or gas mixture is circulated around the products while they pass through the climate chamber, carried by the helically self-stacking conveyor belt.
The method is intended in particular to allow effective circulation of gas around the products in a climate chamber of very compact construction.
The especially characteristic features of the various aspects of the invention emerge from the patent claims below.